The invention relates to an ultrasonic echography and display endoscopic probe and it finds a particularly important, although not exclusive application in the medical field, formed by the optical and echography observation of the internal walls of the human body, especially of the oesophagus, of the stomach and of the duodenum.
Optical endoscopes are already widely used for observing the internal walls or linings of the human body. These endoscopes are formed by a long flexible tube or pipe fixed at one end to a control box comprising members for guiding, by means of fine cables, a rigid end section of the tube. The light is transmitted from an external source to an emitter, placed in the endmost section for illuminating the wall, by means of optical fibers passing through the tube. The optical image collected by a lens situated at the side of the emitter is transmitted by optical fibers to a sighting eyepiece carried by the box.
It has already been proposed (EP-A-00 66 185) to complete such an endoscope with means for the echotomography of the tissues and organs situated behind the walls observed optically. For that, an ultrasonic transducer is implanted in the endmost section, at the side of the optical system. The two methods of exploration are complementary: the optical image allows the ultrasonic translator to be guided and located which is used for supplying the acoustic image. This latter may be of good quality if high frequencies are used, because of the small depth to be explored and because of the absence of highly absorbing tissues interposed between the translator and the organ.
The echotomography endoscope described in document EP-A-00 66 185 uses a single transducer having a mechanical sweep system for causing it ot oscillate about an axis which coincides with that of the endmost section, This technique presents, among other drawbacks, difficulties in forming the relatively moving parts and difficulties in detecting the movement of the transducer. So it is when this latter is fixed and when the orientation of the ultra-sonic beam is modified by means of a rotating mirror.
It is an object of the invention to provide an improved ultrasonic echography and display endoscopic probe. It is a more particular object to provide a probe which may have a wide acoustic angular field without using mobile parts, high resolution and a possibility of optical guiding, while keeping dimensions comparable to those of conventional probes.
To this end, an endoscopic probe according to the invention comprises a tubular member for insertion in a cavity to be explored, having a flexible part ending in an endmost section which is orientatable through mechanical control means disposed inside the flexible part, optical image return and illumination means and an ultrasonic electro-acoustic translator carried by said section, characterized in that the translator comprises a curved linear array of piezoelectric elements fixed in the section, the convexity of the curve being directed outwardly, which array is associated with an electronic circuit for energizing the element according to a sectorial sweep sequence in an angular field overlapping the field of view of the optical means.
The linear array will be generally formed by a single line of piezoelectric elements, the sectorial sweep taking place in a plane passing through the axis of the endmost section. The electronic circuit will generally comprise electric delay and/or phase shift means for providing not only an electronic sweep by energizing successive groups of elements, but also focusing of the array at a given distance. To the sectorial sweep achieved because of the convex form of the array may be added a sweep obtained by modifying the phase and/delay distribution during successive burst from the same group of piezoelectric elements, following a technique comparable to that used in phased plane arrays.
The material construction of the probe may take on very different forms depending on the application envisaged. There will be described hereafter, by way of examples, embodiments intended for the medical field, but a probe of the same kind may be used in numerous industrial fields, for exploring regions of machines or installations inaccessible without dismantling.
The invention will be better understood from reading the following description of probes which form particular embodiments thereof, given by way of non limiting examples.